Web Services (Part 1)Service-Oriented Architecture Overview

ITEC 625 Web Development

Fall 2006

Reference:

Web Services and Service-Oriented Architectures (The Savvy Manager’s Guide, Chapters 1-3), Douglas K. Barry, Morgan Kaufmann, 2003

Basic Definitions

Web Services are the technologies that allow for making connections.

Services are connected together using Web Services, the endpoint of a connection with an underlying computer system that supports the connection.

Service-oriented architectures are made up from the combination of services (internal and external); the architecture of composite applications.

Expected Benefits fromWeb Services and Service-Oriented

Architectures(Is it all hype?)

Expanded Information Technology options More flexible and responsive IT systems Reduced development time Reduced maintenance costs

The Story of a Business Trip (in the not-too-distant future)

Air travel, reservations, modifications Car rental, maps, directions Visiting customers Trip planning Calendar synchronization Customer notes Office communications Handheld device interaction Elmo graphic, p. 10.

Customer Contact Information(from External CRM Service)

Ease of moving between CRM products due to online repository.

Standardization of types of messages and data exchanges with the CRM systems.

Assumption: Industry consortia able to develop the standards.

Data transfers are via XML.

Online Calendar Services Traveler, spouse, manager, customer Each calendar potentially maintained by a

different online service. User establishes rules for data. Software agent enforces the rules which can

be used to monitor and report changes. Communication with other agents: travel,

airline, hotel software agents. Standardization of data interchanges is critical. Auto retrieval from the online repository.

Updates to Customers/Clients

Rules for notification of changes Automatic notification Via cell phone or text messaging for

example. No more manual logging in to check if

there are changes.

Travel Agency Service An external service Entirely automated

• Based on user profile• Preferred airline seating, rental car with GPS, preferred

hotels, • Containing rules for calendar updates

Priority customer information (e.g., visits) sent to Travel Agency for scheduling.

Interaction with other software agents• Handling of emails, notification of any schedule changes.• Dinner changes, time changes• Coordination with car rental for GPS rental.

Other Services Car Rental Service

• Receipt of updated itinerary• Programming into GPS

Airlines and Hotel• Checking status of flights from handheld

As always, standardization is key. • Relatively easy to swap out one service provider for

another.• Services may be seen as commodities.• Competition will result along lines of cost and

innovation.

Analogies ofService-Oriented Architectures

and Web Services

AV systems have parallels between component structure (s-o architecture) and connection paths (web services).

Industry will define standard capabilities of CRM, ERP, other services which will become like commodities.

Connections via Web Services using XML• Continued compatibility with EDI, CORBA, DCOM

Future trends? Fewer organizations writing software, more buying software.

Elmo graphic, p. 20.

Noteworthy Comments… Use of service-oriented architectures

• Organizations of any size can use them.• No cost• Fee-for-use basis• Monthly fees

Blurring of internal/external services• Easily interchanged• Vendors will compete on basis of features and innovations

that are independent of connections.• User interfaces, automated software agents, rule-based

systems, user profiles for customized interactions.

• Internal development will be difficult.• Switching external services will become easy, if not

satisfied with results.

The Basics of Web Services

Web Services Description Language (WSDL) Universal Description, Discovery, and

Integration (UDDI) Simple Object Access Protocol (SOAP) XML Tagged message formats (rather than

fixed record formats) Options besides XML Security and Authorization

Web Services Description Language (WSDL) Forms the foundation for Web Services Service Providers first:

• Describe service using WSDL.• Publish this definition to a directory of services which could

use UDDI or other. Service Consumers then:

• Issues query(s) to the directory to locate a service• Receive details on requests and responses and how to

communicate with that service.• Send XML service request to provider using the WSDL

Service Providers send XML service response based on WSDL back to the consumer.

Elmo graphic, p.23.

Universal Description, Discovery, and Integration (UDDI)

Search of UDDI registry is intended as means of discovering Web Services using WSDL• Contact information and

• Web Services available for various organizations.

UDDI registry is also a way to keep up-to-date on the Web Services an organization currently uses.

Simple Object Access Protocol (SOAP) (no longer an acronym)

Used to send all messages between directories, providers, and consumers.

Generally uses HTTP for connections. This will help drive the adoption of Web

Services. Elmo graphic, p. 25.

• CustomerInfoRequest

• CustomerInfoResponse

Using XML with WSDL Tagged message format Elmo graphic, p. 26. Data retrieved is not dependent upon the order

of the tagged information. Unexpected or additional elements pose no

problem (e.g., in case of updated directory information)

Elmo graphics, p. 27, 29, 30, 31, 32 Messages are much longer using XML Options besides XML

• E.g., for performance reasons• Provider/consumer must agree on formats, if not XML.

Security and Authorization

Often the reason given for not using Web Services.

Many topics being worked at OASIS and W3C• XML-based

• Access, rights of resources, secure encoding, service provisioning

• Assertions, authentication, authorization

• Signatures, encryption, key management

Options besides XML

Both provider and consumer must agree on the message formats, if not XML.